Configuration

Everything is configured in one object, passed to new Lyn(). Every option is optional: new Lyn() alone is a working app.

const app = new Lyn({
  env: {
    port: { name: "PORT", type: "number" },
  },
  database: { schema },
  cors: { origin: ["https://app.example.com"] },
  rateLimit: { max: 100 },
  server: { hostname: "0.0.0.0", allowedHosts: ["api.example.com"] },
});

Application

Option	What it does	Page
env	Declares the environment variables your app needs, checked and typed at startup	Environment variables
database	Connects Postgres, with a typed db in every handler	Database

Security

Option	What it does	Page
cors	Lets browsers on other domains call your API	CORS
rateLimit	Limits how many requests each client may send	Rate limiting

Server

Option	Default	Page
server.hostname	"127.0.0.1", this machine only	Who can reach it
server.allowedHosts	127.0.0.1, localhost, ::1	Who can reach it
server.maxBodyBytes	1048576 (1 MiB)	Limits
server.requestTimeoutMs	30000 (30 seconds)	Limits
start.hideLynLogo	false	Starting

Outside the constructor

• Logging is configured with the NODE_ENV and LOG_LEVEL environment variables. See Logging.
• lyn.config.ts only tells the lyn db commands where your schema and migrations are. See Migrations.